In many dental applications, a working model of a patient's teeth is needed that faithfully reproduces the patient's teeth and other dental structures, including the jaw structure. The model is typically created by first taking an impression of both the upper and lower jaws using an impression material such as alginate or polyvinylsiloxane (PVS). Once the impressions have set, a plaster or stone compound is poured into each of the impression trays to create the dental models for both the upper and lower jaws. Because the physical models are generally made using a separate impression tray for the upper and lower jaw impressions there is not an absolute way of determining the complete jaw alignment using only the cast upper and lower jaw models.
Conventionally, to determine the proper occlusal relationship between the teeth on the upper and lower jaws, a wax bite registration impression is taken. In determining bite registration a common approach typically conforms a sheet of wax to an arch shape and positions the wax intra-orally between a patient's upper and lower dental arches. For example, a wax bite can be obtained by inserting a thin sheet of wax into the patient's mouth and having them bite down on the wax thus leaving a bite mark on both sides of the wax sheet.
As an alternative to wax sheets a material such as a quick setting impression paste may be applied to both sides of a thin mesh and the coated mesh then placed into the patient's month whereupon the patient is asked to bite down on the coated mesh. Once the coating material becomes firm, the coated mesh with the bite registration impression is removed from the month.
The dentist or dental laboratory can then use the bite registration impression to align the cast of the upper jaw dental model into its bite impression marks while also aligning the cast of the lower jaw dental model into its corresponding bite impression marks on the opposing side of bite registration impression. With both cast jaw dental models aligned in their corresponding bite impression marks, the dentist or dental laboratory technician can directly view the correct full occlusion position of the jaws and teeth.
This alignment technique may be used to place corresponding marks or surfaces on the upper and lower jaw models to facilitate viewing the aligned models at a future time without the need to re-align with the bite registration impression. Alternatively, the alignment technique using the bite registration impression may also be used to position the upper and lower jaw castings for mounting in an articulator jig. After installation in the articulator jig, the proper alignment of the upper and lower jaw models may be rechecked using the bite registration impression.
While wax sheets or impression material coated meshes are commonly used for bite registration impressions, potential problems with these bite impressions includes the propensity for the impressions to warp, bend, distort and/or become brittle, depending on how the impression is handled, stored, and used. If the bite impression is compromised or lost, the patient's dentist or dental provider may need to retake the entire set of measurement and the patient's treatment may need to be completely revised based on the retake. In addition, the bite impression must be shipped to the dental laboratory for use in aligning the upper and lower jaw dental model castings. This requirement to ship the relatively fragile bite impression adds cost and time to the treatment process and increases the risk that the bite impression may be damaged or lost.
Systems which focus on taking occlusion measurements electronically have been developed to provide a diagnostic tool for occlusal analysis. U.S. Pat. No. 3,349,489 titled MULTIPLE CELLED PRESSURE SENSITIVE DENTAL DEVICE FOR MEASURING RELATIVE OCCLUSAL PRESSURES by John Shackelford discloses a pressure sensitive device adapted to be positioned between the teeth of a patient with flanges which engage the lingual and buccal sides of the teeth to aid in placing the and holding the device during a test bite. During a test bite, the pressure sensor output may be read from a meter that indicates the relative location of the patient's dental occlusions.
U.S. Pat. No. 4,402,326 titled OCCLUSION PRESSURE IMAGE SYSTEM by Michiaki Okano et. al. discloses an occlusion pressure sensor and an image display system that provides a visual display of occlusal pressure in the form of a black-and-white or color brilliance image on a CRT display.
U.S. Pat. No. 4,521,186 titled SYSTEM FOR DETERMINING THE FIRST PREMATURITY CONTACT OF DENTAL OCCLUSION by Harold Wodlinger et. al. discloses a system for determining the first dental occlusion prematurity. The disclosed system is comprised of an intra-oral sensor with embedded electrical contacts and a liquid crystal display that indicates the location of the occlusion prematurity relative to the edges of the intra-oral sensor.
U.S. Pat. No. 4,856,993 titled PRESSURE AND CONTACT SENSOR SYSTEM FOR MEASURING DENTAL OCCLUSION by William L. Maness et. al. discloses a method and apparatus for using a contact sensor for measuring the force between dental contact points as the jaw is closed on the sensor surface A commercial system is available that uses this technology to measure both biting time profiles and forces and thereby provides a graphical indication of the patient's occlusal force deviation from a “normal” occlusal force balance.
The electronics based dental occlusion measuring systems disclosed in the above U.S. patents are limited for use in aligning the physical jaw dental models in that while they do provide a visual indication of the two-dimensional occlusion contact points, this information is not readily usable by a dentist or dental laboratory technician to quickly orient and align the contact surfaces of the three-dimensional upper and lower jaw dental models. Further, the displayed visual information on the occlusal contacts is generally not available at the dental laboratory where the jaw models are fabricated and the occlusion alignment of the jaw dental models is performed.
U.S. Pat. No. 6,364,660B1 titled METHOD AND SYSTEM FOR IMAGING AND MODELING DENTAL STRUCTURES by Durbin et. al discloses a method and apparatus for mapping the structure and topography of dental formations such as periodontium and teeth, both intact and prepared, for diagnosis and dental prosthetics and bridgework by using an intra-oral image scanning technique. When digital three-dimensional (3D) models of the upper and lower jaws are created, by utilizing such an intra oral scanning system, the bite registration of the upper and lower jaws is not measured since the scanning takes place with the jaws partially open. A method of obtaining a digital representation of the occlusal bite registration that can be transferred to a dental laboratory for use in fabricating a replicate bite registration impression model for determining the occlusal alignment of the upper and lower jaw dental models is now addressed.